// @(#)VSFIFOQueue.java   9/2005
// Copyright (c) 1998-2005, Distributed Real-time Computing Lab (DRCL) 
// All rights reserved.
// 
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// modification, are permitted provided that the following conditions are met:
// 
// 1. Redistributions of source code must retain the above copyright notice,
//    this list of conditions and the following disclaimer. 
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//    this list of conditions and the following disclaimer in the documentation
//    and/or other materials provided with the distribution. 
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package drcl.util.queue;

import java.util.*;
//import drcl.RecycleCan;

/**
 * Variable-size version of {@link FIFOQueue}.
 */
public class VSFIFOQueue extends VariableSizeQueueImpl
    implements java.io.Serializable
{
  //public static RecycleCan elementCan = new RecycleCan(_Element.class, 5, 5);
                          
  _Element head = new _Element(Double.NaN, null);
  _Element tail = null;
  int size = 0;
  int length;
  
  public void reset()
  {
    // recycle all the Elements
    _Element e_= head.next;
    while (e_ != null) {
      _Element tmp_ = e_.next;
      e_.recycle();
      e_ = tmp_;
    }
    head.next = tail = null;
    size = length = 0;
  }
  
  public void enqueue(double key_, Object element_, int size_)
  {
    _Element e_ = head;
    _Element new_ = _Element.create(key_, element_, size_);
    
    if (tail == null) head.next = new_;
    else tail.next = new_;
    tail = new_;
    size += size_; length ++;
  }
  
  public boolean enqueueAfter(Object previousElement_, Object element_, 
          int size_)
  {
    double key_ = retrieveKey(previousElement_);
    if (Double.isNaN(key_)) return false;
    
    _Element new_ = _Element.create(key_, element_, size_);
    _Element e_ = head.next;
    for (; e_.obj != previousElement_; e_ = e_.next);
    
    // insert after e_
    new_.next = e_.next;
    e_.next = new_;
    size += size_; length ++;
    if (new_.next == null) tail = new_;
    return true;
  }
  
  public boolean enqueueAt(int pos_, double key_, Object element_, int size_)
  {
    _Element e_= head;
    for (int i=0; i<pos_ && e_.next != null; i++, e_ = e_.next);
    
    // insert after e_
    _Element new_ = _Element.create(key_, element_, size);
    new_.next = e_.next;
    e_.next = new_;
    size += size_; length ++;
    if (new_.next == null) tail = new_;
    return true;
  }
  
  
  public void merge(Queue that_)
  {
    double[] keys_ = (double[]) that_.keys();
    Element[] elements_ = that_._retrieveAll();
    
    if (keys_.length != elements_.length) return; // XXX: throw exception?
    if (keys_.length == 0) return;
    
    if (tail == null) tail = head;
    for (int i=0; i<keys_.length; i++)  {
      int size_ = elements_[i].getSize();
      _Element new_ = _Element.create(keys_[i], elements_[i].getObject(),
              size_);
    
      tail.next = new_;
      tail = new_;
      size += size_; length ++;
    }
  }
  
  
  public void enqueue(Object element_, int size_)
  {
    _Element new_ = _Element.create(tail == null? Double.NaN: tail.key, element_, size_);
    if (tail == null) head.next = new_;
    else tail.next = new_;
    tail = new_;
    size += size_; length ++;
  }
  
  public Object dequeue()
  {
    if (head.next == null) return null;
    _Element e_ = head.next;
    Object o_ = e_.obj;
    head.next = e_.next;
    size -= ((Element)e_).getSize(); length --;
    if (size == 0) tail = null;
    e_.recycle();
    return o_;
  }
  
  
  public Object dequeue(double key_)
  {
    for (_Element e_ = head; e_.next != null; e_ = e_.next)  
      if (e_.next.key == key_) {
        _Element out_ = e_.next;
        Object o_ = out_.obj;
        e_.next = out_.next;
        size -= ((Element)out_).getSize(); length --;
        if (size == 0) tail = null;
        else if (e_.next == null) tail = e_;
        out_.recycle();
        return o_;
      }
    return null;
  }
  
  
  public Object remove(double key_, Object element_)
  {
    if (head == null) return null;
    for (_Element e_ = head; e_.next != null; e_ = e_.next) {
      _Element tmp_ = e_.next;
      Object o_ = tmp_.obj;
      if (key_ == tmp_.key && (o_ == element_ || o_ != null && o_.equals(element_))) {
        e_.next = tmp_.next;
        size -= ((Element)tmp_).getSize(); length --;
        if (size == 0) tail = null;
        else if (e_.next == null) tail = e_;
        tmp_.recycle();
        return o_;
      }
    }
    return null;
  }
  
  public Object remove(Object element_)
  {
    for (_Element e_ = head; e_ != null && e_.next != null; e_ = e_.next) {
      _Element tmp_ = e_.next;
      Object o_ = tmp_.obj;
      if (o_ == element_ || o_ != null && o_.equals(element_)) {
        e_.next = tmp_.next;
        size -= ((Element)tmp_).getSize(); length --;
        if (size == 0) tail = null;
        else if (e_.next == null) tail = e_;
        tmp_.recycle();
        return o_;
      }
    }
    return null;
  }
  
  public void removeAll(Object element_)
  {
    for (_Element e_ = head; e_ != null && e_.next != null; e_ = e_.next) {
      _Element tmp_ = e_.next;
      Object o_ = tmp_.obj;
      if (o_ == element_ || o_ != null && o_.equals(element_)) {
        e_.next = tmp_.next;
        size -= ((Element)tmp_).getSize(); length --;
        if (size == 0) tail = null;
        else if (e_.next == null) tail = e_;
        tmp_.recycle();
      }
    }
  }
  
  
  public void removeAll(double key_, Object element_)
  {
    for (_Element e_ = head; e_ != null && e_.next != null; e_ = e_.next) {
      _Element tmp_ = e_.next;
      Object o_ = tmp_.obj;
      if (tmp_.key == key_ &&  (o_ == element_ || o_ != null && o_.equals(element_)) )  {
        e_.next = tmp_.next;
        size -= ((Element)tmp_).getSize(); length --;
        if (size == 0) tail = null;
        else if (e_.next == null) tail = e_;
        tmp_.recycle();
      }
      else if (tmp_.key > key_) break;
    }
  }
  
  
  public Object remove(int n_)
  {
    _Element e_= head;
    for (int i=0; i<n_ && e_.next != null; i++, e_ = e_.next);
    
    if (e_.next == null) return null;
    _Element tmp_ = e_.next;
    Object o_ = tmp_.obj;
    e_.next = tmp_.next;
    size -= ((Element)tmp_).getSize(); length --;
    if (size == 0) tail = null;
    else if (e_.next == null) tail = e_;
    tmp_.recycle();
    
    return o_;
  }
  
  public Object firstElement()
  { return head.next == null? null: head.next.obj; }
  
  public double firstKey()
  { return head.next == null? Double.NaN: head.next.key; }
  
  public Object lastElement()
  { return tail == null? null: tail.obj; }
  
  public double lastKey()
  { return tail == null? Double.NaN: tail.key; }
  
  public Object retrieveAt(int n_)
  {
    _Element e_= head.next;
    for (int i=0; i<n_ && e_ != null; i++, e_ = e_.next);
    
    return e_ == null? null: e_.obj; 
  }
  
  public double retrieveKeyAt(int n_)
  {
    _Element e_= head.next;
    for (int i=0; i<n_ && e_ != null; i++, e_ = e_.next);
    
    return e_ == null? Double.NaN: e_.key; 
  }
  
  public Object retrieveBy(double key_)
  {
    for (_Element e_ = head; e_.next != null; e_ = e_.next)
      if (e_.next.key == key_) return e_.next.obj;
      else if (e_.next.key > key_) return null;
    return null;
  }
  
  public Object[] retrieveAll(double key_)
  {
    Vector v_ = new Vector();
    for (_Element e_ = head; e_.next != null; e_ = e_.next)  
      if (e_.next.key == key_) v_.addElement(e_.next.obj);
    Object[] oo_ = new Object[v_.size()];
    v_.copyInto(oo_);
    return oo_;
  }
  
  public Object[] retrieveAll()
  {
    Object[] all_ = new Object[length];
    _Element e_ = head.next;
    for (int i=0; i<all_.length; i++) {
      all_[i] = e_.obj;
      e_ = e_.next;
    }
    return all_;
  }
  
  public Element[] _retrieveAll()
  {
    Element[] all_ = new Element[length];
    _Element e_ = head.next;
    for (int i=0; i<all_.length; i++) {
      all_[i] = e_;
      e_ = e_.next;
    }
    return all_;
  }
  
  public double retrieveKey(Object o_)
  {
    for (_Element e_ = head.next; e_ != null; e_ = e_.next)
      if (e_.obj.equals(o_)) return e_.key;
    return Double.NaN;
  }
  
  public boolean contains(Object element_)
  { 
    for (_Element e_ = head.next; e_ != null; e_ = e_.next)
      if (e_.obj.equals(element_)) return true;
    return false;
  }
  
  public boolean containsKey(double key_)
  { 
    for (_Element e_ = head; e_.next != null; e_ = e_.next)
      if (e_.next.key == key_) return true;
    return false;
  }
  
  public double[] keys()
  {
    double[] keys_ = new double[length];
    _Element e_ = head.next;
    for (int i=0; i<keys_.length; i++) {
      keys_[i] = e_.key;
      e_ = e_.next;
    }
    return keys_;
  }

  public Enumeration getKeyEnumerator()
  { return new MyEnumerator(this, true); }
  
  public Enumeration getElementEnumerator()
  { return new MyEnumerator(this, false); }
  
  static class MyEnumerator extends drcl.DrclObj implements Enumeration
  {
    boolean forKey;
    _Element current;
    
    public MyEnumerator (VSFIFOQueue q_, boolean forKey_)
    {
      forKey = forKey_;
      current = q_.head;
    }
    
    public boolean hasMoreElements()
    {  return current.next != null;  }
    
    public Object nextElement()
    {
      if (current.next == null) return null;
      Object r_ = forKey? new drcl.data.DoubleObj(current.next.key): current.next.obj;
      current = current.next;
      return r_;
    }
  }
    
  public int getSize()
  {  return size;  }
  
  public int getLength()
  {  return length;  }
  
  public String oneline()
  {
    StringBuffer sb_ = new StringBuffer(super.toString() + "," + getSize() + "/" + getLength());
    
    for (_Element e_ = head.next; e_ != null; e_ = e_.next)
      sb_.append("-----" + e_.key + ":" + e_.obj);
    
    return sb_.toString();
  }
}
